Preheat the oven to gas 3, 170°C, fan 150°C. Grease and line a 16 x 16 centimeters square tin. In a bowl, combine the flour, a pinch of salt and the baking powder.
In a large bowl, beat to cream the butter and sugars until light and fluffy. Add the egg and vanilla and beat again until the mixture is smooth.
Add the flour mixture and beat for another minute. Stir in the white chocolate and gently fold in the raspberries. Spread the dough into the prepared tin, sprinkle with the almonds and bake for 40 minutes.
Leave to cool completely in the tin. Cover tightly with foil until you're ready to cut into slices.